While Greenland ranks among the coldest spots on Earth, it is getting warmer.

How much warmer? In July, orbiting satellites recorded unprecedented above-freezing temperatures
spanning Greenland’s ice sheet, which is three times larger than Texas.

The development, which carries troubling implications for sea levels, was something that
climatologist Jason Box saw coming. In fact, he described it in the journal
Cryosphere in February 2012.

“It was an elementary prediction,” said Box, a professor at the Geologic Survey of Denmark and
Greenland in Copenhagen. “The snow pack could not endure another similar summer without melting.”T
he problem was Box, who had been a researcher at Ohio State University’s Byrd Polar Research
Center, and other climatologists thought that melting across the entire sheet would occur sometime
in the next 10 years.

Now he is itching to go back to Greenland where he can test a new theory about the thaw.On his
24th expedition to Greenland, which he hopes to start by June, he wants to examine how black carbon
affects melting. They are the tiny soot particles carried by global winds from distant wildfires,
power plants and car engines.

The particles, which absorb sunlight and heat, reduce the natural reflective properties of ice.
Ice that absorbs more heat melts faster. How much can be blamed on soot? No one knows.“It’s just
not that well understood,” Box said.

Then again, just how climate change is affecting Greenland’s ice sheet isn’t well understood
either.Greenland’s ice seems to be melting faster than usual, but there are only about 30 years of
satellite observations and computer models to work with.

“It’s a relatively short span of data,” said C.K. Shum, a geodetic scientist at the Byrd Polar
Research Center and a lead author of the International Panel on Climate Change’s report on ocean
impacts and sea-level rise.

More data, he said, are needed to show how ice builds up and recedes over centuries.

Melting in summer months is typical for southern low-lying sections of the ice. Even during the
warmest summers, ice in the north and at higher elevations stayed intact. And the amount of ice
grew or at least remained steady with each winter’s snow.Expeditions to the ice are necessary, Shum
said, to gain a better understanding of what’s actually going on as ice in these areas now is
melting.

“The better we can estimate the current rate of ice sheet melting, the better we can explain why
the sea level is rising as it is now,” he said.

Melting glaciers worldwide raise sea levels about 0.08 inch a year. Estimates provided by Shum
and NASA show that Greenland’s melting ice sheet adds as much as 0.03 inch annually.Although that
doesn’t seem like a lot, said Richard Williams, a glaciologist at the Woods Hole Coastal and Marine
Science Center in Massachusetts, the levels continue to rise and might be increasing at a faster
rate.

Greenland is so important because there is enough ice there to raise the world’s oceans by more
than 20 feet, which would devastate island nations and coastal cities worldwide.“We know the sea
level is going up, but how fast is it going to go up?” Williams said. “That’s the key question. You
need the observational data to try to determine what exactly is going on.”

Box sees his black carbon investigation as a missing ingredient to his February 2012 study,
which measured the ice sheet’s decreasing ability to reflect light.

The study found that higher summer temperatures melt each winter’s snow accumulation faster.
This exposes the glacial ice underneath to sunlight sooner each season.

Tiny bits of dirt and dust carried by snow mix with dust on the ice left during previous
seasons. All of these impurities lead to more melting, Box said.As a result, the albedo there — the
measure of ice reflectivity — is the worst that researchers have recorded since 2000. In some
areas, the study found that the rate of melting has doubled.

Box said he thought about the effect of black carbon when large wildfires raged through Colorado
last summer.

Of all the impurities that contaminate ice and absorb heat, “black carbon is the most potent,”
Box said. “Small increases in black carbon have a very strong effect on reducing reflectivity.”

The issue will become even more important as the number of wildfires increases — another
consequence of climate change.

Box said he wants to collect 10-foot-long cores of ice and snow from three locations on the ice
sheet. These cores then could be tested for carbon content.